Answer: Fur stuffed with feathers.
Explanation:
Ball games were popular throughout ancient history but also in the Middle Ages. Many of these games are the forerunners of today's American football and soccer. There are data on almost all continents on how peoples practiced some ball sports in antiquity. The game balls' look was not like today, it was mostly egg-shaped, and the materials for making it were different. The most common material for making the ball was leather, which was filled with feathers.
Newton's law of universal gravitation states that a particle attracts every other particle in the universe using a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
Work needed = 23,520 J
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Further explanation
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Given
height = 12 m
mass = 200 kg
Required
work needed by the crane
Solution
Work is the transfer of energy caused by the force acting on a moving object
Work is the product of force with the displacement of objects.
Can be formulated
W = F x d
W = Work, J, Nm
F = Force, N
d = distance, m
F = m x g
Input the value :
W = mgd
W = 200 kg x 9.8 m/s²x12 m
W = 23520 J
(a) If the balloon is suspended in air and it drifts neither up nor down, it means the forces acting on it are equally balanced. There are only two forces acting on the balloon:
- its weight, of magnitude 1 N, directed downward
- the buoyant force, directed upward
The two forces are balanced, so the buoyant force in this case is equal to the weight of the balloon: 1 N.
(b) when the buoyant force decreases, the weight becomes greater than the buoyant force. This means there is now a net force on the balloon, acting downward, so the balloon starts to drift toward the ground.
(c) when the buoyant force increases, it becomes greater than the weight. This means there is now a net force on the balloon, acting upward, so the balloon starts to go up.